Since the advent of wireless cellular technology, the handoff or handover process has been one of the most critical aspects of a wireless network's dropped call performance. Handover relates to transferring a phone call from a source cell to a target cell to avoid terminating or dropping the call, e.g., when an associated mobile device moves away from the source cell. Conventionally, two types of handover exist: hard handover and soft handover. Hard handover utilizes a break-then-make procedure in which a channel of a source cell associated with a call is released before another channel in a target cell is utilized for the call. Soft handover utilizes a make-then-break procedure in which the channel of the source cell is used while the channel of the target cell is used—connection to the target cell is established before breaking the connection to the source cell. Accordingly, soft handover techniques reduce call drop compared to hard handover.
Conventional hard handover technology can reduce call drop by assigning different biases, e.g., offsets, during handover based on different signal quality conditions. For example, wireless providers can set a high handover bias when signal quality and/or conditions are high; otherwise, the wireless providers can set a lower handover bias when signal quality and/or conditions are reduced. However, conventional hard and soft handover techniques do not optimize cell coverage and/or handover reliability because such handovers do not occur during optimal source and target cell signal levels.
For instance, one issue with conventional hard handover technology is that a source cell signal may not successfully complete handover operations when the source cell signal was of low quality before a handover was triggered. For example, handover can be triggered when a mobile device is stationary due to signal fading or degradation. If a low quality source cell signal fades or further degrades proximate to a handover, an associated call can be dropped as a result of failed handover operations. Another issue with conventional hard handover technology is that a source cell signal can fade or further degrade during a time resources of a target cell are allocated to affect a handover—an associated call is dropped when the source cell signal can not support the handover.
One issue with conventional soft handover technology is that a delay during active set additions can result in a dropped call. An active set is a list of target cells that can be utilized during a soft handover, which varies as an associated mobile terminal moves; a target cell can be added to/deleted from the active set based on a location of the mobile terminal relative to a location of the target cell. If a source cell signal fades, or “fast fades,” between a time a target cell is selected to be added as an active set addition, but before the active set addition is triggered, a call can drop because of failed decodes associated with poor source cell signal quality.
The above-described deficiencies of today's wireless communication networks and related technologies are merely intended to provide an overview of some of the problems of conventional systems, and are not intended to be exhaustive. Other problems with the state of the art, and corresponding benefits of some of the various non-limiting embodiments described herein, may become further apparent upon review of the following detailed description.